In conventional systems, Global Navigation Satellite System (GNSS) signals are employing new modulation techniques to increase the overall system performance. However, these modulations introduce multiple peaks to the autocorrelation function. This can cause a receiver to track a wrong peak of the autocorrelation function resulting in biased pseudorange measurements.
For example, in conventional systems, the incoming signal may have multiple peaks in its autocorrelation function. Typically, in order to reduce the complexity of the receiver, this signal is being tracked by correlating the incoming signal with a locally generated binary offset carrier (BOC) signal replica. This incoming signal may be a composite binary offset carrier (CBOC) or any other complex BOC signal. The cross-correlation function of the BOC signal shows two side peaks located at a given offset (for example, ±0.5 chips) from the center peak. The receiver can lock to these side peaks unless some protection mechanism is utilized to prevent side peak tracking.
Conventionally, the baseband channel in the GNSS receiver responsible for tracking BOC modulated signals includes five correlators: Very Early, Early, Prompt, Late, and Very Late. The Prompt correlator is responsible for tracking the center peak and the Very Early and the Very Late correlators are spaced at ±0.5 chip distance apart from the Prompt correlator. If a side peak is tracked, it can be detected by observing a higher amplitude in either of the two correlators with respect to the prompt correlator. If the amplitude in one of these two correlators is larger than the amplitude of the prompt correlator for several integration periods, it is concluded that the receiver is tracking a side peak of the signal and the local signal replica is moved by the given offset. This is known as the bump jumping technique. However, the inclusion and use of the Very Early and Very Late Correlators in the conventional bump jumping technique leads to an increased complexity in the baseband tracking channel design, thus, increasing the cost of the GNSS receiver.
For the reasons stated above and for other reasons stated below, it will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for a less complex baseband tracking channel design with fewer correlators to detect side peak tracking in the baseband tracking channel.